This invention relates to image projection devices and, more particularly, to a device for connecting a lamp assembly to a lamp assembly frame.
Projection systems have been used for many years to project motion pictures and still photographs onto screens for viewing. More recently, multimedia projection systems have become popular for conducting sales demonstrations, business meetings, and classroom instruction.
In a common operating mode, multimedia projection systems receive analog video signals from a personal computer (xe2x80x9cPCxe2x80x9d). The video signals may represent still, partial-, or full-motion displays. A projection engine of these multimedia projection systems includes a light source, an image-forming device, and optical components for directing images onto a screen. Lamp modules include a lamp-reflector assembly having a concave reflector and a lamp or burner accurately mounted near the focal point of the concave reflector. Because lamps have limited life expectancy, lamp modules are designed to be replaced in the field by a user of the projection system.
Significant effort has been invested into developing projectors producing bright, high-quality color images. However, the optical performance of conventional projections is often less than satisfactory. For example, suitable projected image brightness is difficult to achieve, especially when using compact portable color projectors in a well-lighted room. The intensity of the light that can be generated by the lamp is one limitation of compact projectors. To maximize the intensity of light directed toward the image-forming device, an elliptical reflector is often used in the lamp-reflector assembly instead of a spherical or parabolic reflector. However, for optimal results, the reflectors must be accurately positioned relative to a light-path aperture of the projection engine within true position and parallelism tolerances of approximately (plus/minus) 0.002 inch (0.05 mm), making it impractical to adjust the position of the lamp-reflector assembly after it is installed in the projector.
Lamp modules in current projection systems are mounted by various devices such as one or a combination of brackets, plates, clips, and screws. For example, one prior art device includes a mounting bracket for a lamp-reflector assembly that has opposed channels sized to slide onto mounting rails located within a projector to precisely position the mounting bracket without the use of tools. The lamp-reflector assembly is securely held in place against an adjustment plate by a spring clip. The adjustment plate includes a key that fits into a groove on the lamp-reflector assembly to maintain the rotational position of the lamp-reflector assembly. Screws extend through oversized holes in the adjustment plate and are threaded into holes in the mounting bracket. The oversized holes allow the position of the adjustment plate to be adjusted during assembly. One problem that exists with this mounting system is that accurate positioning of the lamp-reflector assembly on the adjustment plate is difficult because the key and groove arrangement is formed in sheet metal. Additionally, this system is expensive to manufacture because it requires so many different elements, namely, the mounting bracket, adjustment plate, spring clip, and screws. All of these components are metal, adding to the cost and weight of the projector, which is undesirable in portable projection units.
An object of the present invention is, therefore, to provide a device for retention and accurate alignment of a lamp assembly in a lamp module assembly.
Another object of the present invention is to provide a single retention and alignment device that eliminates the need for multiple elements and supplemental parts.
Yet another object of the present invention is to provide a lamp retention and alignment device that is quick and easy to assemble without the need for tools.
An image projector includes a light source that directs light toward an image-forming device containing electronic and optical components for generating color images in response to an external data signal received by the image projector for projection onto a screen. The light source is a lamp module removably housed within the image projector. The lamp module includes a lamp assembly having a high intensity arc lamp mounted within a reflector. The lamp assembly is positioned and held within a lamp assembly frame by a retainer clip so that when the lamp module is located within the image projector light from the lamp assembly is accurately directed toward the image-forming device for projection onto a screen.
The retainer clip comprises a single piece of flexible sheet metal having a main body with a central opening to receive the lamp assembly and an extension portion that extends over the top of the lamp assembly and frame and snaps over the front face of the frame to secure it. The lamp assembly is further secured to the frame by a snap-in connection that includes upstanding posts on the frame with shoulders that snap into openings in the retainer clip. The retainer clip provides a simple yet secure three point attachment for connecting the lamp assembly to the frame so that the lamp module is accurately positioned to direct light along a light path toward the image-forming device and does not need to be adjusted.
Additional objects and advantages of this invention will be apparent from the following detailed description of preferred embodiments thereof which proceeds with reference to the accompanying drawings.